Low Hydrogen Electrode Classification Question 1

[Ryan86]

Im studying for the CWI exam for my retest I failed the code book portion for the exam. One thing that I am stumped on is low hydrogen electrode designation. Heres where im stuck. The question reads: What is the minimum preheat temperature for welding a 1 inch thick ASTM A36 plate with an E7018 electrode? Now I know what the answer is it's 50 degrees. What im puzzeled on is that in table 3.2 in the D1.1 2010 edition, for ASTM 36 plate preheat and interpass temp theres two answers SMAW with other then hydrogen electrodes or SMAW with low hydrogen electrodes. Now obviously an E7018 electrode is a low hydrogen electrode because the answer is in the low hydrogen electrode preheat specification. What my question is, is what designates an electrode to be low hydrogen or other then low hydrogen? I know that A5.1 classifies for steel electrodes and A5.5 classifies for low alloy electrodes. But I also found that low hydrogen electrodes can be classified in either A5.1 or A5.5. Stumped if I run into another question asking similar like E6010 or E7028 how do I know where to look, either in low hydrogen electrodes or other then low hydrogen electode? Please help thanks.

 

[SectionIX]

If I understand your question, a SMAW electrode with the four digit designation ending with 5,6, or 8 will signify a LH electrode.

E701x
E801x

x = 5, 6 or 8 is a LH electrode

 

[metengr]

Under AWS classification, like AWS 5.5, for low hydrogen designation the diffusible hydorgen designator must be described. This reqires testing to be performed under AWS 5.5 of low hydrogen electrode classifications.

So, for AWS E7018 the suffix designator would be defined as either E7018- H16, H8, or H4, etc.,

 

[Ryan86]

Ohhh ok I see yeah listed in the F groups is the designation, also after looking at the 5,6, or 8 at the end of the classification. Anything in F group F4 or ending with a 5,6,8 is a LH electrode. thanks Guys!!